Drilling method and apparatus



April 4, 1967 w P, MCKMN 3,312,292

DRILLING METHOD AND APPARATUS Filed May 18, 1964 4 Sheets-Sheet 1 KNVENTOR Walter P. Mc Kain April 4, 1967 w. P. M KAIN DRILLING METHOD AND APPARATUS Filed. May 18 1964 4 Sheets-Sheet 2 U as ' INVENTOR I Walter P. Mc Kuin aw a April 4, 1967 w. P. MCKAIN 3,312,292

DRILLING METHOD AND APPARATUS Filed May 18, 1964 4 Sheets-Sheet 5 Fig .IO.

INVENTOR Walter P. Mc Kain April 4, 1967 w. P. M KAlN DRILLING METHOD AND APPARATUS 4 Sheets-Sheet 4 Filed May 18, 1964 g wul t i l ls h z Kuin %zM/M United States Patent ()1 3,312,292 DRILLING METHOD AND APPARATUS Walter P. McKain, Parkersburg, W. Va., assignor to Acme Fishing Tool Company, Parkersburg, W. Va., a corporation of West Virginia Filed May 18, 1964, Ser. No. 368,101 16 Claims. (Cl. 173-89) This invention relates to a drilling method and apparatus and particularly to a drilling method and apparatus whereby such control of the drilling operation, either manually or automatically, is accomplished that unprecedented drilling efiiciency is attained and substantially continuously maintained. The invention provides a significant improvement in percussion drilling, i.e., that system of drilling in which an end of a cable carrying a drilling tool is cyclically raised and released, the release thereof on each cycle permitting the drilling tool to fall freely under the force of gravity to act by impact on the material being drilled.

The system of drilling above mentioned is sometimes called the spudder system or spudding. I provide drilling, indicating and control means for use in the spudder system of drilling whereby the new and useful results above mentioned are accomplished.

In the spudder system of drilling the drilling tool is attached to and suspended from one end of the drilling cable which passes over the crown pulley or sheave at the top of the mast of the drilling rig. The other end of the drilling cable is fastened to the bull reel which is used to store the extra cable needed as the drilling tool progressively penetrates the earth. The bull reel may be rotated by the engine to raise the drilling tool out of the well as required. The bull reel may also be secured against rotation by the application of a brake. The drilling tool is lowered into the well by gravity when the brake is released. The brake is controlled by a hand lever cooperating with a rack whereby the brake may be adjusted to and set at a selected degree of tightness. As the drilling cable leaves the bull reel it passes over the heel pulley or sheave and under the spudding sheave which is located on the spudding beam, whence the cable extends generally vertically upwardly along the mast to the crown pulley or sheave and thence downwardly into the well. A pitman connects the movable end of the spudding beam to the crank pin of the spudding gear. Rotation of the spudding gear by the engine causes the movable end of the spudding beam to rise and fall, imparting a vertical reciprocating motion to the drilling tool.

The driller attempts to achieve the optimum rate of penetration into the earth by regulating the engine speed and the brake tension on the bull reel. These two factors are adjusted to conform to varying conditions prevailing as the well deepens and the tool penetrates the various earth strata. The adjustments are effected by the driller based on his judgment dictated by the feel of the line or the impulses he receives by placing his hand on the drilling cable as it moves up and down during the drilling operation. Drilling efficiency depends upon the drillers skill in interpreting the information he receives from such -impulses. Such method of drilling is far from an exact' science; experience indicates that in conventional drilling prior to my invention less than half of the capability of the drilling rig has been utilized.

When the proper engine speed has been established the payout of the drilling cable to compensate for the deepening of the hole is accomplished by two methods, hand feed and automatic feed. With hand feed the brake is normally set to prevent rotation of the bull reel. The driller usually releases the brake periodically as the hole advances to permit the bull reel to pay out the required cable approximately as needed. If the driller permits the 3,312,292 Patented Apr. 4, 1967 ice drill to operate very long without releasing the brake the drilling cable lbecomes tauter till the drilling tool drills off or swings free. This means that because of the deeper hole with the same length of cable, the bit can no longer strike the bottom with destructive force. Obviously if the bit does not strike the bottom of the hole no penetration is accomplished. The drillers attention to the periodic release of the brake is frequently diverted by his various otherduties around the machine so that this condition of reduced or no penetration prevails at frequent irregular intervals. Thus the maximum tension in the drilling cable varies from a relatively high value just before the brake is released to a relatively low value just after the brake has been released. The highest tension occurs in the drilling cable when the drilling tool swings free and cannot strike the bottom. This method of brake tdjlstment is known to those skilled in the art as hand A modified drilling technique known as automatic feed is achieved by adjusting the tension on the brake to such a degree that the tendency to turn the bull reel upon downward movement of the drilling tool results in a slight rotation of the bull reel upon each downward stroke of the drilling tool, thus progressively paying out cable to compensate for the progressively increasing depth of the well. This relatively sensitive adjustment is made by setting the brake control lever with a detent on the side thereof disposed in a selected notch of the rack and thereafter adjusting the position of the rack by turning a vernier nut which is a standard element of a conventional drilling rig, which turning of the vernier nut imparts to the rack and brake control lever what in relation to the frame or chassis of the drilling rig may be. termed a micrometer adjustment. Both the hand feed method and the automatic feed method are well known to those skilled in the art.

The automatic feed method of drilling is not completely satisfactory or truly automatic because the brake responds only to the line load for which it was adjusted and is not necessarily accurately responsive to the deepening of the well. Drillers attempting to use the automatic feed method frequently feed unneeded cable into the well even after drilling progress has completely stopped. Unnecded cable is also sometimes fed into the well when the drilling tool sticks momentarily, as when small rocks are dislodged and fall into the well above the drilling tool. In these instances it is necessary for the driller to disengage the spudding clutch, engage the bull reel clutch, release the bull reel brake and rewind the unneeded cable on the bull reel. Thereafter several minutes are required to resume the spudding motion and re-establish satisfactory drilling progress. This may happen frequently under certain conditions, resulting in much wasted time. The driller may try to avoid such a condition by tightening the brake or even resorting to hand feed; in either case the rate of drilling suffers materially.

The hand feed method of drilling demands greater skill and constant attention from the driller for optimum penetration. It is less satisfactory for drilling hard rock than automatic feed. Hand feed is preferable in drilling soft formations where the problem is not so much one of penetration as it is one of mud-mixing. In soft formations the rate of penetration must be restrained so that the material being drilled will be thoroughly mixed with water introduced into the hole for that purpose. For optimum operation the cuttings must be held in suspension as the well is deepened until they can be removed by bailing. If the drilling tool is allowed to advance too rapidly the drilling mud will not be thoroughly mixed, permitting the cuttings to separate out of suspension as soon as the mud is no longer subjected to the direct churning action of as practicable. I drilling hard formation results in a loose line, producformations results in a tight line causing a heavier load on the crown pulley and the shock absorber mounting the crown pulley.

Efiicient hard rock drilling requires the maximum energy which can be developed by the falling drilling tool. Maximum energy is realized when the drilling tool is allowed to fall freely, i.e., is restrained by the cable as little The proper brake tension applied while ing a lighter load on the crown pulley and shock 1 absorber.

It is impossible for even a highly skilled, experienced driller employing equipment and methods available prior to my invention to accurately estimate the proper tension on the drilling cable under all conditions of drilling and continuously make the adjustments Wl'llCh are necessary to maintain optimum operation.

If the magnitude of the load applied to the crown pulley is measured, as, for example, by a pressure gage, and

the, information is made available to the driller he will be aware at all times of the tension on the drilling cable.

Knowing he needs a tight line (heavy load) for soft formations and a loose line (light load) for hard forload information to the driller can be used to actuate a device which will automatically loosen the brake when the line tension is too high and tighten it when the line tension is too low.

Release of brake tension for automatic feed should occur only at the instant the drilling tool strikes the bottom of the well. This should occur simultaneously with the spudding beam reaching the zenith or top of its stroke. To insure this coordination I have provided means exemplified as a mercury switch which may be mounted on the spudding beam or on the spudding beam heel shaft so that when the spudding beam reaches the zenith of its stroke the mercury switch will be tilted at such an angle as to close an electric circuit lighting an electric light on the main control panel. The light flashes on for a brief period and goes out as the spudding beam descends from its zenith. By observing the movement of the pointer of the pressure gage the driller can adjust the engine speed until the zenith of the pointer swing coincides with the zenith of the spudding beam as indicated -by the flash of the electric light.

The same electric impulse which lights the light may be used to energize means such as a solenoid to open a shut-off valve in a conduit supplying impulses. For example, impulses of hydraulic fluid under pressure, from the crown sheave to brake control means such as a piston operating in a cylinder and connected with the brake control lever rack to adjust the position of the brake control lever analogously to the adjustment above described accomplished in a conventional drilling rig by a vernier nut. By such means the brake may be controlled to permit turning of the bull reel only when the spudding beam is atthe zenith of its stroke. Such an arrangement provides for substantially truly automatic feed 'with minimum likelihood of feeding too much or too little cable which is an inherent defect in the automatic feed method as practiced prior to my invention.

An object of my invention is to provide a relatively simple and inexpensive attachment which may be applied to new or existing spudder type drilling rigs having means to accurately apprise the driller of the information he requires to adjust his controls for the most effective and eflicient drilling. This preferably includes a pressure gage or meter connected to a sensing device measuring the magnitude of the impulses generated by the changing load on the crown pulley. A tachometer may be provided to measure the speed of the engine or spudding beam. Signaling means-electric or hydraulicare preferably provided connected to a sensing device or the spudding beam indicating the zenith of the spudding beam. The pressure gage, tachometer and signaling means are preferably mounted on a panel attached to the drilling rig in clear view of the driller while he is at his drilling station.

Another object is to provide a sensing device, such, for example, as a hydraulic piston and cylinder mechanism or a magnetic strain gage or a hydrulic diaphragm, supporting the crown pulley or mast and generating a hydraulic or electrical impulse of a magnitude directly proportional to the load applied by the drilling cable throughout the drilling stroke cycle.

A further object is to provide a sensing device attached to the spudding beam or the spudding beam heel shaft which can accurately determinethe zenith of the spudding beam during the drilling stroke cycle. Such device may be calibrated in circular arc degrees so that it can be adjusted if desired to indicate a position either preceding or following the zenith of the stroke of the spudding beam. The sensing device may generate an impulse, either electric or hydraulic, of limited duration providing the driller a visual indication that the spudding beam is at its zenith as well as supplying energy to operate automatic brake control means.

A still further object is to provide a device, either hydraulic or electro-magnetic, which will maintain a relatively heavy pressure on the bull reel brake except when operated to release the brake by an impulse or a combination of impulses generated by the sensing devices sensing the load on the crown pulley and the position of the spudding beam.

I provide a method of drilling comprising cyclically raising an end of a cable carrying a drilling tool and releasing the same to permit the drilling tool to fall freely under the influence of gravity, normally holding stationary a portion of the cable remote from said end and releasing said portion of the cable for controlled periods on certain cycles to feed additional cable into the hole being drilled, said periods being the periods while the tool is falling freely during which the hole being drilled is deepened and the tension on the cable exceeds a predetermined value. Preferably said portion of the cable is released on each cycle during the portion of the free fall of the drilling tool due to deepening of the hole being drilled when the hole 1s deepened on such cycle and additional cable is fed into the hole being drilled while said portion of the cable is released and the tension on the cable exceeds a predetermined value.

I further provide a method of drilling comprising cyclically raising one end of a cable whose other end is wound upon a drum and which cable carries a drilling tool at its first mentioned end and releasing the first mentloned end of the cable to permit the drilling tool to fall freely under the influence of gravity, measuring changes in the tension on the cable and braking and releasing the drum to permit paying out of cable upon predetermined increase in the tensoin on the cable, preferably during the portion of the free fall of the drilling tool clue to deepen- .mg of the hole being drilled.

I also provide drilling apparatus comprising a cable carrying a drilling tool, a drum upon which the cable is wound, a brake for the drum, means for applying and releasing the brake, operating means for cyclically raising the cable to raise the drilling tool and releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to turn the drum to pay out cable, control means for altering the speed of the operating means and means including indicating means indicating changes in the tension on the cable, whereby the operator is enabled to operate the control means to alter the speed of the operating means and to operate the means for applying and releasing the brake to obtain optimum drilling effect.

I preferably provide first indicating means indicating changes in the tension on the cable and :means including second indicating means indicating when the operating means are in their extreme position corresponding to full release of the cable. Means are preferably provided for adjusting the magnitude of the braking effort of the brake to permit controlled turning of the drum to pay out cable when the cable is tensi-oned. I preferably provide actuating means responsive to changes in the tension on the cable together with means actuated by the actuating means upon predetermined tensioning of the cable for releasing the brake. Such means actuated by the actuating means are preferably rendered effective by the control means.

I further provide drilling apparatus comprising a cable carrying a drilling tool, a drum upon which the cable is wound, a brake for the drum, the brake being normally effective for holding the drum against turning, operating means to the position releasing the cable to permit drilling tool and releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to turn the drum to pay out cable, a confined fluid whose pressure is responsive to changes in the tension of the cable, control means responsive to movement of the operating means to the position releasing the cable to permit the drilling tool to fall freely under the influence of gravity, a normally closed valve restricting the fluid under pressure, means operated by the control means upon movement of the operating means to said position for opening said valve and means operated by the fluid under pressure released by opening of said valve for releasing the brake. The control means preferably include a switch operable in response to movement of the operating means, and there are preferably provided means including an electric circuit controlled by the switch upon operation thereof upon movement of the operating means to the aforementioned position for opening the valve.

I still further provide drilling apparatus comprising a cable carrying a drilling tool at one end thereof, means acting on the cable at a portion thereof remote from said end normally holding said portion of the cable against endwise movement, means acting on the cable intermediate said end and said portion thereof for cyclically raising said end of the cable and releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending tofeed cable into the hole being drilled, means connected with the cable and acted on thereby upon the cyclic raising and releasing of said end thereof producing a force having predetermined relation to the tension on the ca'ble, actuating means acted on by said force for releasing said portion of the cable to permit feeding of cable into the hole when said force exceeds a predetermined value, mechanism normally rendering said force inoperative to act on said actuating means and control means acting on said mechanism causing the same to render said force operative to act on said actuating means to release said portion of the cable to permit feeding of cable into the hole when said force exceeds -a predetermined value during such portion of the free fall of the drilling tool as is due to deepening of the hole being drilled. The means acting on the cable preferably comprise a spudding beam which raises the end of the cable carrying the drilling tool upon downward movement of the spudding beam and releases the cable to permit the drilling tool to fall freely under the influence of gravity upon upward movement of the spudding beam. The cable is released to permit feeding of cable into the hole when the aforementioned force exceeds a predetermined value when the spudding beam is approaching and within a predetermined distance [from its limit of upward movement. Themeans connected with the cable and acted on thereby upon the cyclic raising and releasing of the end of the cable carrying the drilling tool preferably include confined fluid and means acting thereon subjecting the fluid to pressure. The mechanism normally rendering the fluid under pressure inoperative to act on the actuating means preferably comprises means including a normally closed valve, and the control means preferably act on said means to open the normally closed valve. The control means may comprise an electric circuit including a switch, desirably a mercury switch, which switch is desirably mounted on the spudding beam, acting on the aforementioned mechanism causing the same upon actuation of the switch to one of open and closed positions when the spudding beam is approaching and within a predetermined distance from its limit of upward movement to render the fluid under pressure operative to act on the actuating means to release the cable to permit feeding of cable into the hole when the fluid pressure exceeds a predetermined value.

The drilling apparatus preferably comprises a drum upon which the cable is wound, a brake normally holding the drum against rotation and actuating means for releasing the brake to permit rotation of the drum and consequent feeding of cable into the hole, the brake being released by the fluid under pressure to permit rotation of the drum and consequent feeding of cable into the hole.

In a preferred form my drilling apparatus comprises a cable carrying a drilling tool at one end thereof, a drum upon which the cable is wound, a brake norm-ally holding the drum against rotation, a spudding beam acting on the cable intermediate said end and the drum for cyclically raising by downward movement of the spudding beam said end of the cable and by upward movement of the spudding beam releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to feed cable into the hole being drilled, means connected with the cable and acted on thereby upon the cyclic raising and releasing of said end thereof including confined fluid and means acting thereon subjecting the fluid to pressure having predetermined relation to the tension on the cable, actuating means including a piston spring pressed in one direction and acted on in the opposite direction by the fluid under pressure for releasing the brake to permit rotation of the drum and consequent feeding of the cable into the hole When the fluid pressure exceeds the spring pressure, means including a normally closed valve which when closed prevents the fluid under pressure from acting on the piston and control means comprising an electric circuit including a switch acting on said last mentioned means to open the normally closed valve upon actuation of the switch to'one of open and closed positions when the spudding beam is approaching and within a predetermined distance from its limit of upward movement to establish connection between the fluid under pressure and the piston to move the piston against the pressure of the spring when the fluid pressure exceeds the spring pressure to release the brake to permit rotation of the drum and consequent feeding of cable into the hole.

Other details, objects and advantages of the invention will become apparent as the following description of a present preferred embodiment thereof and a present preferred :method of practicing the same proceeds.

In the accompanying drawings I have shown a present preferred embodiment of the invention and have illustrated a present preferred method of practicing the same in which FIGURE 1 is an elevational view of drilling apparataus embodying my invention;

FIGURE 2 is a fragmentary elevational view to enlarged scale of a portion of the structure shown in FIG- URE 1 including the shock absorber through which changes in tension of the drilling cable are communicated to the hydraulic cylinder;

FIGURE 3 is a vertical cross-sectional view taken on the line III-III of FIGURE 2;

FIGURE 4 is a fragmentary vertical crosssectional view to enlarged scale of the hydraulic cylinder associated with the shock absorber shown in FIGURES 2 and 3;

FIGURE 5 is a fragmentary elevational view to enlarged scale of a portion of the structure shown in FIG- URE 1;

FIGURE 6 is a fragmentary horizontal cross-sectional view taken on the line VIVI of FIGURE 5;

FIGURE 7 is an elevational view to further enlarged scale of the mercury switch which is mounted on the spudding beam with the cover of the switch removed;

FIGURE 8 is a vertical cross-sectional view taken on the line VIII-VIII of FIGURE 7, also showing the mounting means for the mercury switch;

FIGURE 9 is a front elevational view to enlarged scale of the control panel;

FIGURE 10 is a vertical cross-sectional view taken on the line XX of FIGURE 9;

FIGURE 11 is a fragmentary vertical cross-sectional view to enlarged scale taken on the line XIXI of FIG- URE 9;

FIGURE 12 is a fragmentary vertical cross-sectional view to enlarged scale taken on the line XIIXII of FIGURE 9;

FIGURE 13 is a fragmentary vertical cross-sectional view to enlarged scale taken on the line XIIIXIII of FIGURE 9;

FIGURE 14 is a wiring and flow diagram of my drilling apparatus;

FIGURE 15 is a fragmentary elevational view to enlarged scale of a portion of the structure at the lower left hand corner of FIGURE 5; and

FIGURE 16 is a vertical cross-sectional view taken on the line XVIXVI of FIGURE 15.

Referring now more particularly to the drawings, the drilling rig is designated generally by R and is illustrated in the drawings as a mobile rig mounted on a truck chassis. The drilling rig itself, apart from my novel control mechanism, is conventional, comprising a mast 2, a bull reel 3 on which is stored the drilling cable 4, a spudding beam 5 mounted for pivotal oscillation in a generally vertical plane about the generally horizontal axis of the heel shaft 6 and having a spudding sheave 7 and a heel sheave 8 slidably and rotatably mounted on the heel shaft 6, the drilling cable 4 passing from the bull reel 3 over the heel sheave 8 and under the spudding sheave 7 and over the crown pulley or sheave 9 at the top of the mast 2. The drilling tool is carried by the lower end of the cable extending downwardly from the crown pulley 9 at the left of FIGURE 1.

The engine 10 is belt-connected to the main belt pulley 11 which rotates the jack shaft 12. The spudding pinion 13 rotates the spudding gear 14. Pitman 15 is connected to the spudding gear 14 by a crank 'pin 16 and to the spudding beam 5 by the pitman pin 18. Rotation of the spudding gear 14 by the engine 10 causes the free end of the spudding beam 5 to rise and fall in a generally vertical plane with an approximate simple harmonic motion as related to the path of the crank pin 16. The pudding pinion 13 is loose on the jack shaft 12 and connectable with the jack shaft to rotate therewith by a clutch 13a of any conventional type. A bull reel driving pinion 3a is loose on the jack shaft 12 and connectable with the jack shaft to rotate therewith by a clutch 3b of any conventional type. The bull reel driving pinion 3a is in mesh with a gear 3c fixed to the bull reel. Thus the engine 10 may drive the spudding beam or the bull reel at the will of the operator.

The bull reel 3 may be prevented from rotating or subjected to a frictional drag by a brake band 17 which encircles the brake drum 19 fixed to the bull reel. With the reeled end of the cable held stationary by the bull reel with the brake tightly set the vertical motion of the spudding beam 5 causes the drill tool to be raised and lowered in the well or hole being drilled. The pressure applied to the bull reel brake is controlled by a hand lever 20. All of the mechanism described up to this point may be conventional.

In my preferred arrangement the crown pulley 9 is mounted atop the mast 2 through a shock absorber 21 carried by an annular cylinder 22 receiving an annular piston 23 carried by and connected to a plate 24 rigidly fastened to the mast 2. The shock absorber may be positioned elsewhere in the drilling apparatus, as, for example, on the spudding beam, or it may be omitted entirely. The crown pulley 9 is carried by a shaft 25 whose ends pass through openings 25a in a steel bracket 28 and are mounted in opposed wooden blocks 26. The wooden blocks 26 and the steel bracket 28 partake during drilling of vertical sliding movement in the mast. The bottom plate 28a of the bracket 23 seat on the top plate 21a of the shock absorber 21, which may be of any conventional or suitable construction. A guide pin 27 is threaded into the plate 28a and is locked by a nut 29 threaded onto the top of the pin and against the plate 28a and extends down through the shock absorber and the cylinder 22 in guiding relationship thereto. A ring 36 threaded onto the cylinder 22 limits upward movement of the cylinder relatively to the piston 23'. The piston is sealed to the cylinder by O-rings 31. Compression springs 32 normally urge the cylinder upwardly relatively to the piston.

A flexible hydraulic hose 33 extends from the piston 23 wherein it communicates with the space 34 between the piston and cylinder through a duct 35 in the piston. The hose 33 is connected through a manifold 33a to a pressure gage 36 through conduits shown in FIGURE 14, the pressure gage 36 being carried by the control panel 37 which is mounted on the main belt guard 38 at approximately eye height at the drillers station.

A mercury'switch 39 is mounted on the end of the heel shaft 6 so that the center of the mercury switch is substantially at the axis of the heel shaft. This permits the mercury switch to oscillate about its own center as the heel shaft 6 oscillates due to the action of the spudding beam 5 without excessive agitation of the mercury. The mercury switch 39 comprises a mercury capsule 40 from which extend leads 41 and 42. The lead 41 is connected through a wire 43 with a signal light 44 on the control panel 37 from which a wire 45 extends to a ground terminal 46 on the chassis. The engine battery 47 has one terminal connected with the ground terminal 46 through a wire 48 and has the other terminal connected to an onoif switch 49 by a wire 50. The lead 42 from the mercury capsule 40 is connected to the on-off switch 49 by a wire 51. The magneto 52 of the engine 10 is connected with the ground terminal 46 by a wire 53 and also is connected by a wire 54 with the tachometer 55 mounted on the control panel 37. The dial of the tachometer may be for convenience calibrated in strokes per minute of the spud ding beam A wire 56 extends from the tachometer 55 to the wire 45 as shown in FIGURE 14.

Mounted on the chassis is a hydraulic brake control cylinder 57. When my invention is applied to an existing drilling rig the brake control cylinder 57 replaces the vernier nut above referred to normally applied atop the brake lever rack stud. The hydraulic hose 33 is connected with the brake control cylinder 57 by conduits 58, 59, 60 and 61. The conduit 58 extends to a normally closed solenoid operated valve 62 from which the conduit 60 extends to a T 63 which is connected with the conduit 59 through a check valve 64 and with the brake control cylinder 57 through the conduit 61. The check valve 64 permits flow of hydraulic fluid therethrough only in the downward direction; when hydraulic fluid attempts to flow upwardly through the check valve the valve closes and prevents upward flow. Wires 65 and 66 extend from the solenoid 67 operating the valve 62, the wire 65 being connected with the wire 43 and the wire 66 being extending to the ground terminal 46 as shown in FIGURE 14.

The conduits are filled with hydraulic fluid so that the variable load applied to the crown pulley 9'during drilling causes periodic increase and decrease in the pressure of the hydraulic fluid in the flexible hydraulic hose 33 and the conduits and other elements connected therewith. This variable pressure is measured by the pressure gage 36 on the control panel and is transmitted to the solenoid opera-ted valve 62 and through that valve, when the valve is open, to the brake control cylinder 57. When the pressure exerted on the hydraulic fluid by the cylinder 22 increases the hydraulic fluid tends to flow in the direction of the arrows in FIGURE 14. When such pressure decrease-s the hydraulic fluid tends to flow in the opposite direction. The check valve 64 permits the brake control cylinder 57 to discharge into the line Whenever the pressure drops regardless of whether the solenoid operated valve 62 is open or closed. The duration of maximum pressure will frequently exceed the time the solenoid valve is permitted to remain open by the mercury switch 39 so it is necessary to provide for escape of hydraulic fluid from the brake control cylinder; otherwise the brake would remain released until the solenoid valve is next energized to open the valve 6 2. This would nullify the purpose of the valve which is to limit the release of the brake to a predetermined restricted interval, as will presently be described.

The brake lever rack is designated 68 and has slots 68a selectively cooperable with a dete-nt 69 on the brake lever 20 as shown in FIGURE 16. The cylinder 57 is carried by a bracket 70 on the chassis, the bracket has a portion of fork shape receiving, as shown in FIGURE 16, an element 71 constituting the lower portion of the cylinder to which the upper portion of the cylinder is threaded at 72. Extending upwardly from the rack as is the brake lever rack stud 73 to which is threadedly connected at its upper end, as shown in FIGURE 16, a piston designated generally by reference numeral 74 which is slidably fitted in a bushing 75 in the element 71. The piston 74 has a reduced zone 76 opposite the conduit 61 surmounted by a zone 77 of relatively great diameter slidably fitted in a bushing 78 in the upper portion of the cylinder 57 and sealed thereto by an O-ring 79. Below the conduit 61 the piston is also sealed to the cylinder by an O-ring 80. The piston is urged downwardly by a compression coil spring 81 biased against a nut 82 threaded into the upper end of the cylinder. A stop screw 83 is threaded into the nut 82 and locked in adjusted position relative thereto by a lock nut 84 for limiting upward movement in the cylinder of the piston 74. The bracket 70 also has a downwardly extending portion 70a and headed studs 700 are threaded thereinto and pass through vertically elongated slots 7% in the rack 68 for vertically guiding the rack upon movement of the piston 74 in the cylinder 57.

Pressure applied through the conduit 61 tends to raise the piston 74 in the cylinder 57. When the piston 74 is raised in the cylinder 57 the rack 68 is raised and the brake is loosened. The spring 81 opposes upward movement of the piston. The pressure applied to the piston by the spring may be adjusted by adjusting the nut 82. The downward spring pressure on the piston is designed to prevent upward movement of the rack 68 and brake lever 20 until the pressure applied to raise the piston exceeds a predetermined amount.

The on-otf switch 49 is used to shut off the electric current from the battery 47 when desired. Opening of that switch renders the hydraulic brake control cylinder 57 and the signal light 44 inoperative. A needle valve 85 below the pressure gage 36 may be used to render the pressure gage inoperative when not required. A hydraulic fluid tank or reservoir is shown at 86. A pump 87 is provided which may be employed to increase the hydraulic pressure in the system to any desired level. The pump piston when reciprocated draws hydraulic fluid from the tank 86 (the upper ball valve, FIGURE 14,

In opening to permit such withdrawal) and forces the hy'-' draul-ic fluid into the system through the conduit 87a (the lower ball valve, FIGURE 14, opening to permit passage of the hydraulic fluid into the conduit 87a). A cylinder 88 has a piston 89 disposed therein whose position in the cylinder is determined by a screw 90 on which the piston is mounted. This provides a micrometer adjustment of the pressure in the system to the precise level desired once the approximate pressure level has been attained by means of the pump 87. A manual pressure release valve 91 is provided which when desired may relieve the pressure of the system to the tank 86 through the pipe 92. A damper 93 is provided between the pressure release valve 91 and the needle valve 85.

The mercury switch 39 is shown in FIGURE 7. It comprises a casing 94 in which is mounted a setting hand 95 by means of a screw 96, the setting hand 95 being turnable about the axis of the screw relatively to a dial 97. A clip 98 is mounted on the setting hand 95 by means of a screw 99, and the mercury-containing capsule 40 is grippingly held by the clip 98 as shown in FIGURE 7. The setting hand 95 may be retained in desired adjusted positions by tightening the screw 96. After the drilling rig has been set up for drilling and levelled the mercury-containing capsule 40 is positioned so that the mercury therein closes an electric circuit between the leads 41 and 42 at the zenith of the spudding beam stroke. This may be done by positioning the setting hand 95 at 90 as shown in FIGURE 7 and rotating the clip 98 carrying the mercury-containing capsule 40 about the axis of the screw 99 until the mercury just makes contact. After the initial setting is made the angle for dwell may be adjusted accurately in arc degrees by moving the setting hand 95 as required.

The operation will now be described. The drilling tool is bottomed in the well and then raised a short dis tance so that when the drilling motion is begun the tool reciprocates freely and does not strike bottom. The spudding beam is set at its zenith. With the brake set and the spudding clutch disengaged the drilling tool will hang motionless. The mercury switch on the heel shaft 6, to which the spudding beam 5 is rigidly connected, is adjusted to make contact as above described. When the electrical circuit is closed through the mercury switch the signal light 44 on the control panel is illuminated. At this point the drilling tool is exerting its full static load on the crown pulley 9. Because the drilling cable 4 has a double reach between the spudding sheave 7 and the drilling tool (up over the crown sheave 9 and down again) the load applied to the crown pulley and the pressure cylinder 22 is double the dead weight of the drilling tool and cable. The driller pumps fluid pressure into the system suflicient to approximately counterbalance the dead weight of the drilling tool and cable. He then accurately adjusts the pressure so that the needle of the pressure gage 36 points to a selected reference number such, for example, as 100. If the system pressure should change during drilling due to a change in temperature or some other cause the initial pressure can be re-established by repeating the procedure just described to bring the needle of the pressure gage 36 to the same reference number on the dial.

After attending to the preliminaries just described the driller starts the drilling motion in the usual manner. As the drilling tool moves up and downs-till not striking bottom in the well-the needle of the pressure gage swings back and forth as the load on the crown pulley varies. The signal light flashes on at the zenith of each stroke of the spudding beam and the needle of the pressure gage swings at its maximum. The operator increases the motor speed and the needle of the pressure gage develops a double swing-a minor swing as the falling drilling tool catches up with the beam and a major swing when the spudding beam reaches its zenith and pickup of the drilling tool occurs. The speed of the motor is further in ll creased until the minor swing is absorbed by the major swing. The swing of the needle of the pressure gage now coincides with the flash of the signal light and the driller has achieved optimum drilling motion without guesswork.

The driller makes note of the magnitude of the maximum swing of the needle of the pressure gage which represents the maximum normal load which can be applied to the drilling tool which should occur only when the drilling tool does not strike bottom. As the drilling proceeds the driller uses this as a reference point. He also notes the speed from the tachometer. These data enable him to immediately establish optimum drilling motion on any subsequent drilling operation using the same weight of drilling tool and cable. Some adjustment may be required as the well deepens and more cable enters the well, increasing the total load on the crown pulley.

After the proper motion has been established the driller loosens the brake and allows the drilling tool to strike bottom. The swing of the needle of the pressure gage will be less than the free-swing maximum in proportion to the amount of energy absorbed when the drilling tool strikes bottom. This is constantly apparent to the driller and enables him to make such adjustments as may be required to maintain optimum drilling conditions without guessing. The automatic brake control can be adjusted to maintain definite magnitude of impact delivered upon the material being drilled at each drilling cycle. This is always indicated on the pressure gage. Once the optimum drilling conditions have been estab lished by the driller they can be re-established quickly without guesswork on subsequent drilling operations following bailing or other circumstances requiring cessation or removal of the drilling tool from the well.

While I have shown and described a present preferred embodiment of the invention and have illustrated a present preferred method of practicing the same it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

I claim:

1. Drilling apparatus comprising a cable carrying a drilling tool, a drum upon which the cable is wound, a brake for the drum, means for applying and releasing the brake, operating means for cyclically raising the cable to raise the drilling tool and releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to turn the drum to pay out cable, control means for altering the speed of the operating means and means including indicating means indicating changes in the tension on the cable, whereby the operator is enabled to operate the control means to alter the speed of the operating means and to operate the means for applying and releasing the brake to obtain optimum drilling effect.

2. Drilling apparatus comprising a cable carrying a drilling tool, a drum upon which the cable is wound, a brake for the drum, means for applying and releasing the brake, operating means for cyclically raising the cable to raise the drilling tool and releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to turn the drum to pay out cable, control means for altering the speed of the operating means, means including first indicating means indicating changes in the tension on the cable and means including second indicating means indicating when the operating means are in their extreme position corresponding to full release of the cable.

3. Drilling apparatus comprising a cable carrying a drilling tool, a drum upon which the cable is wound, a brake for the drum, operating means for cyclically raising the cable to raise the drilling tool and releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to turn the drum to pay out cable, means for adjusting the magnitude of the braking eflect of the brake to permit controlled turning of the drum to pay out cable when the cable is tensioned during the portion of the free fall of the drilling tool due to deepening of the hole being drilled, means including first indicating means indicating changes in the tension on the cable and means including second indicating means indicating when the operating means are in their extreme position corresponding to full release of the cable.

4. Drilling apparatus comprising a cable carrying a drilling tool, a drum upon which the cable is wound, a brake for the drum, the brake being normally effective for holding the drum against turning, operating means for cyclically raising the cable to raise the drilling tool and releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to turn the drum to pay out cable, actuating means responsive to changes in the tension on the cable and means actuated by the actuating means upon predetermined tensioning of the cable for releasing the brake.

5. Drilling apparatus comprising a cable carrying a drilling tool, a drum upon which the cable is wound, a brake for the drum, the brake being normally effective for holding the drum against turning, operating means for cyclically raising the cable to raise the drilling tool and releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to turn the drum to pay out cable, actuating means responsive to changes in the tension on the cable, control means responsive to movement of the operating means to the position releasing the cable to permit the drilling tool to fall freely under the influence of gravity and means actuated by the actuating means upon predetermined tensioning of the cable and rendered effective by the control means for releasing the brake.

6. Drilling apparatus comprising a cable carrying a drilling tool, a drum upon which the cable is wound, a brake for the drum, the brake being normally effective for holding the drum against turning, operating means for cyclically raising the cable to raise the drilling tool and releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to turn the drum to pay out cable, a confined fluid whose pressure is responsive to changes in the tension on the cable, control means responsive to movement of the operating means to the position releasing the cable to permit the drilling tool to fall freely under the influence of gravity, a normally closed valve restricting the fluid under pressure, means operated by the control means upon movement of the operating means to said position for opening said valve and means operated by the fluid under pressure released by opening of said valve for releasing the brake.

7. Drilling apparatus comprising a cable carrying a drilling tool, a drum upon which the cable is wound, a brake for the drum, the brake being normally effective for holding the drum against turning, operating means for cyclically raising the cable to raise the drilling tool and releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to turn the drum to pay out cable, a confined fluid whose pressure is responsive to changes in the tension on the cable, control means including a switch operable in response to movement of the operating means to the position releasing the cable to permit the drilling tool to fall freely under the influence of gravity, a normally closed valve restricting the fluid under pressure, means including an electric circuit controlled by said switch upon operation thereof upon movement of the operating means to said position for opening said valve and means operated by the fluid under pressure released by opening of said valve for releasing the brake.

8. Drilling apparatus comprising a cable carrying a drilling tool at one end thereof, means acting on the cable at a portion thereof remote from said end normally holding said portion of the cable against endwise movement, means acting on the cable intermediate said end and said portion thereof for cyclically raising said end of the cable and releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to feed cable into the hole being drilled, means connected with the cable and acted on thereby upon the cyclic raising and releasing of said end thereof producing a force having predetermined relation to the tension on the cable, actuating means acted on by said force for releasing said portion of the cable to permit feeding of cable into the hole when said force exceeds a predetermined value, mechanism normally rendering said force inoperative to act on said actuating means and control means acting on said mechanism causing the same to render said force operative to act on said actuating means to release said portion of the cable to permit feeding of cable into the hole when said force exceeds a predetermined value during such portion of the free fall of the drilling tool as is due to deepening of the hole being drilled.

9. Drilling apparatus comprising a cable carrying a drilling tool at one end thereof, means acting on the cable at a portion thereof remote from said end normally hold ing said portion of the cable against endwise movement, a spudding beam acting on the cable intermediate said end and said portion thereof for cyclically raising by downward movement of the spudding beam said end of the cable and by upward movement of the spudding beam releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to feed cable into the hole being drilled, means connected with the cable and acted on thereby upon the cyclic raising and releasing of said end thereof producing a force having predetermined relation to the tension on the cable, actuating means acted on by said force for releasing said portion of the cable to permit feeding of cable into the hole when said force exceeds a predetermined value, mechanism normally rendering said force inoperative to act on said actuating means and control means acting on said mechanism causing the same to render said force operative to act on said actuating means to release said portion of the cable to permit feeding of cable into the hole when said force exceeds a predetermined value when the spudding beam is approaching and within a predetermined distance from its limit of upward movement.

10. Drilling apparatus comprising a cable carrying a drilling tool at one end thereof, means acting on the cable at a portion thereof remote from said end normally holding said portion of the cable against endwise movement, a spudding beam acting on the cable intermediate said end and said portion thereof for cyclically raising by downward movement of the spudding beam said end of the cable and by upward movement of the spudding beam releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to feed cable into the hole being drilled, means connected with the cable and acted on thereby upon the cyclic raising and releasing of said end thereof including confined fluid and means acting thereon subjecting the fluid to pressure having predetermined relation to the tension on the cable, actuating means acted on by the fluid under pressure for releasing said portion of the cable to permit feeding of cable into the hole when the fluid pressure exceeds a predetermined value, mechanism normally rendering the fluid under pressure inoperative to act on said actuating means and control means acting on said mechanism causing the same to render the fluid under pressure operative to act on said actuating means to release said portion of the cable to permit feeding of cable into the hole when the fluid pressure exceeds a predetermined value when the spudding beam is approaching and within a predetermined distance from its limit of upward movement.

11. Drilling apparatus comprising a cable carrying a drilling tool at one end thereof, means acting on the cable at a portion thereof remote from said end normally holding said portion of the cable against endwise movement, a spudding beam acting on the cable intermediate said end and said portion thereof for cyclically raising by downward movement of the spudding beam said end of the cable and by upward movement of the spudding beam releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to feed cable into the hole being drilled, means connected with the cable and acted on thereby upon the cyclic raising and releasing of said end thereof including confined fluid and means acting thereon subjecting the fluid to pressure having predetermined relation to the tension on the cable, actuating means acted on by the fluid under pressure for releasing said portion of the cable to permit feeding of cable into the hole when the fluid pressure exceeds a predetermined value, means including a normally closed valve normally rendering the fluid under pressure inoperative to act on said actuating means and control means acting on said last mentioned means to open the normally closed valve to render the fluid under pressure operative to act on said actuating means to release said portion of the cable to permit feeding of cable into the hole when the fluid pressure exceeds a predetermined value when the spudding beam is approaching and within a predetermined distance from its limit of upward movement.

12. Drilling apparatus comprising a cable carrying a drilling tool at one end thereof, means acting on the cable at a portion thereof remote from said end normally holding said portion of the cable against endwise movement, a spudding beam acting on the cable intermediate said end and said portion thereof for cyclically raising by downward movement of the spudding beam said end of the cable and by upward movement of the spudding beam releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to feed cable into the hole being drilled, means connected with the cable and acted on thereby upon the cyclic raising and releasing of said end thereof including confined fluid and means acting thereon subjecting the fluid to pressure having predetermined relation to the tension on the cable, actuating means acted on by the fluid under pressure for releasing said portion of the cable to permit feeding of cable into the hole when the fluid pressure exceeds a predetermined value, mechanism normally renclering the fluid under pressure inoperative to act on said actuating means and control means comprising an electric circuit including a switch acting on said mechanism causing the same upon actuation of the switch to one of open and closed positions when the spudding beam is approaching and within a predetermined distance from its limit of upward movement to render the fluid under pressure operative to act on said actuating means to release said portion of the cable to permit feeding of cable into the hole when the fluid pressure exceeds a predetermined value.

13. Drilling apparatus comprising a cable carrying a drilling tool at one end thereof, a drum upon which the cable is Wound, a brake normally holding the drum against rotation, a spudding beam acting on the cable intermediate said end and the drum for cyclically raising by downward movement of the spudding beam said end of the cable and by upward movement of the spud-ding beam releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to feed cable into the hole being drilled, means connected with the cable and acted on thereby upon the cyclic raising and releasing of said end thereof including confined fluid and means acting thereon subjecting the fluid to pressure having predetermined relation to the tension on the cable, actuating means acted on by the fluid under pressure for releasing the brake to permlt rotation of the drum and consequent feeding of cable into the hole when the fluid pressure exceeds a predetermined value, mechanism normally rendering the fluid under pressure inoperative to act on said actuating means and control means acting on said mechanism causing the same to render the fluid under pressure operative to act on said actuating means to release the brake to permit rotation of the drum and consequent feeding of cable 15 into the hole when the fluid pressure exceeds a predetermined value when the spudding beam is approaching and within a predetermined distance from its limit of upward movement.

14. Drilling apparatus comprising a cable carrying a drilling tool at one end thereof, means acting on the cable at a portion thereof remote from said end normally holding said portion of the cable against endwise movement, a spudding beam acting on the cable intermediate said end and said portion thereof for cyclically raising by downward movement of the spudding beam said end of the cable and by upward movement of the spudding beam releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to feed cable into the hole being drilled, means connected with the cable and acted on thereby upon the cyclic raising and releasing of said end thereof including confined fluid and means acting thereon subjecting the fluid to pressure having predetermined relation to the tension on the cable, actuating means acted on by the fluid under pressure for releasing said por tion of the cable to permit feeding of cable into the hole when the fluid pressure exceeds a predetermined value, mechanism normally rendering the fluid under pressure inoperative to act on said actuating means and control means comprising an electric circuit including a mercury switch mounted on the spudding beam acting on said mechanism causing the same upon actuation of the switch to one of open and closed positions when the spudding beam is approaching and within a predetermined distance from its limit of upward movement to render the fluid under pressure operative to act on said actuating means to release said portion of the cable to permit feeding of cable into the hole when the fluid pressure exceeds a predetermined value.

15. Drilling apparatus comprising a cable carrying a drilling tool at one end thereof, a drum upon which the cable is wound, a brake normally holding the drum against rotation, a spudding beam acting on the cable intermediate said end and the drum for cyclically raising by downward movement of the spudding beam said end of the cable'and by upward movement of the spudding beam releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to feed cable into the hole being drilled, means connected with the cable and acted on thereby upon the cyclic raising and releasing of said end thereof including confined fluid and means acting thereon subjecting the fluid to pressure having predetermined relation to the tension on the cable, actuating means acted on by the fluid under pressure for releasing the brake to permit rotation of the drum and consequent feeding of the cable into the hole when the fluid pressure exceeds a predetermined value, means in cluding a norm-ally closed valve normally rendering the fluid under pressure inoperative to act on said actuating means and control means comprising an electric circuit including a switch acting on said last mentioned means to open the normally closed valve upon actuation of the switch to one of open and closed positions when the spudding beam is approaching and within a predetermined distance from its limit of upward movement to render the fluid under pressure operative to act on said actuating means to release the brake to permit rotation of the drum and consequent feeding of cable into the hole when the fluid pressure exceeds a predetermined value.

16. Drilling apparatus comprising a cable carrying a drilling tool at one end thereof, a drum upon which the cable is wound, a brake normally holding the drum against rotation, a spudding beam acting on the cable intermediate said end and the drum for cyclically raising by downward movement of the spudding beam said end of the cable and by upward movement of the spudding beam releasing the cable to permit the drilling tool to fall freely under the influence of gravity, tending to feed cable into the hole being drilled, means connected with the cable and acted on thereby upon the cyclic raising and releasing of said end thereof including confined fluid and means acting thereon subjecting the fluid to pressure having predetermined relation to the tension on the cable, actuating means including a piston spring pressed in one direction and acted on in the opposite direction by the fluid under pressure for releasing the brake to permit rotation of the drum and consequent feeding of the cable into the hole when the fluid pressure exceeds the spring pressure, means including a normally closed valve which when closed prevents the fluid under pressure from acting on the piston and control means comprising an electric circuit including a switch acting on said last mentioned means to open the normally closed valve upon actuation of the switch to one of open and closed positions when the spudding beam is approaching and within a predetermined distance from its limit of upward movement to establish connection between the fluid under pressure and the piston to move the piston against the pressure of the spring when the fluid pressure exceeds the spring pressure to release the brake to permit rotation of the drum and consequent feeding of cable into the hole.

References Cited by the Examiner UNITED STATES PATENTS 2,121,078 6/1938 Elines 17322 2,587,638 3/1952 Meier 173'10 2,658,725 11/1953 Arps 173-21 2,715,015 8/1955 Thomburg 17310 2,742,267 4/1956 Meier 1731O 2,795,396 6/1957 Davidson 17310 FRED C. MATTERN, JR., Primary Examiner.

L. P. KESSLER, Assistant Examiner. 

1. DRILLING APPARATUS COMPRISING A CABLE CARRYING A DRILLING TOOL, A DRUM UPON WHICH THE CABLE IS WOUND, A BRAKE FOR THE DRUM, MEANS FOR APPLYING AND RELEASING THE BRAKE, OPERATING MEANS FOR CYCLICALLY RAISING THE CABLE TO RAISE THE DRILLING TOOL AND RELEASING THE CABLE TO PERMIT THE DRILLING TOOL TO FALL FREELY UNDER THE INFLUENCE OF GRAVITY, TENDING TO TURN THE DRUM TO PAY OUT CABLE, CONTROL MEANS FOR ALTERING THE SPEED OF THE OPERATING MEANS AND MEANS INCLUDING INDICATING MEANS INDICATING CHANGES IN THE TENSION ON THE CABLE, WHEREBY THE OPERATOR IS ENABLED TO OPERATE THE CONTROL MEANS TO ALTER THE SPEED OF THE OPERATING MEANS AND TO OPERATE THE MEANS FOR APPLYING AND RELEASING THE BRAKE TO OBTAIN OPTIMUM DRILLING EFFECT. 